1. Field of the Invention
This invention relates to cannulas and, more particularly, to a cannula which is oval-shaped in cross section and therefore ideally suited for use in minimally invasive surgical procedures.
2. Description of the Related Art
Cannulas have a wide variety of applications during surgical procedures. For example, in coronary surgery, venous and arterial cannulas are used to conduct blood between the body and bypass equipment. Cannulas are used to conduct cardioplegia solution for both antigrade and retrograde solution administration, and cannulas are also used as vents, sumps, and for chest tube fluid suction. The structure for these known cannulas generally comprises a cannula body which is circular in cross section and has at least one lumen extending therethrough which is similarly circular in cross section. Examples of these structures are seen in U.S. Pat. Nos. 4,639,252; 4,129,129; and 5,395,330.
A recent trend in surgical procedures is to minimize the size of the access apertures formed in the chest cavity. These procedures include mini-sternomoty and minimally invasive cardiac surgery. In each of these procedures, the goal is to reduce the size of the aperture in the chest wall. One problem in achieving this goal is the size, geometry, and space requirements for the instruments, cannulas, and the like which must pass through the reduced size apertures.